JP2003316172A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which has an intermediate transfer belt, fixing belt, etc., and assures releasability from a toner, etc., by applying a release agent in the stage of use to the surfaces of the intermediate transfer belt, the fixing belt, etc., and which can suppress the adhesion of the surfaces of the intermediate transfer belt, the fixing belt, etc., to the toner in the initial stage of their use particularly without generating the contamination by coating with the release agent. <P>SOLUTION: The surfaces of the intermediate transfer belt, the fixing belt, etc., used in the image forming apparatus are coated with the release agent, such as dimethyl silicone oil, in at least the stage of their no use and the coated surfaces are subjected to a pretreatment for release to allow a touching member to touch these surfaces. The pretreatment for release consists of the treatment to perform an adhesion increasing treatment to increase the adhesion of the intermediate transfer belt, etc., to the toner images on the surfaces in combination before or simultaneously with the coating application of the release agent. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a printer, a copying machine, a multi-function machine or the like, which forms a toner image by utilizing an electrophotographic system, and more particularly, an image formed from the toner image has a glossy feeling. The present invention relates to an image forming apparatus capable of forming an excellent image on a recording sheet.

[0002]

2. Description of the Related Art In recent years, as an image forming apparatus for obtaining an image having excellent image gloss, a toner image formed according to image information is carried on a belt-shaped image carrier, and the toner on the image carrier is carried. There has been proposed an image forming apparatus of a system in which an image is at least heated and pressed to transfer and fix the image on a recording sheet supplied so as to come in contact with the surface of the image carrier (Japanese Patent Laid-Open No. 10-63028). .

FIG. 31 is a conceptual view of a main part of an example of the image forming apparatus. In this image forming apparatus, the toner image formed on the photosensitive drum 110 is transferred by the transfer device 150 onto the intermediate transfer belt 200 rotating in the arrow direction in the image forming unit 100 using the electrophotographic method, and then the belt heating member 2 is heated.
For example, the toner 10 is heated to the softening point of the toner. Then, the heated toner image on the intermediate transfer belt 200 is pressed against the intermediate transfer belt 200 with the intermediate transfer belt 200 sandwiched between them.
It is transferred and fixed on the recording paper P supplied to the pressure contact portion between the 20 side and the intermediate transfer belt 200. In the transfer fixing of the toner image, the recording paper P after passing through the pressure contact portion is conveyed in a state of being in close contact with the intermediate transfer belt 200, and then when the recording paper P reaches the peeling roll 220, the intermediate transfer belt 2 is transferred.
Completed by peeling from 00. By carrying out such transfer fixing, a toner image having a high smoothness is formed on the recording paper P as if the surface smoothness of the intermediate transfer belt 200 was transferred as it is, and an image excellent in glossiness is obtained. You can Reference numeral 230 in the drawing is a belt support roll, and 240 is a cleaning roll for cleaning the surface of the intermediate transfer belt 200.

As the intermediate transfer belt 200 in such an image forming apparatus, a surface layer made of an elastic material is formed on the belt base material from the viewpoint of improving the adhesion between the belt surface and the recording paper. It is said that a double structure is suitable. Examples of the surface layer include those formed of the following rubber materials and resin materials.

First, a surface layer formed of silicone rubber can be mentioned. In this surface layer, good elasticity, adhesiveness to the toner at room temperature, and releasability from the molten toner can be obtained, while the interaction between the silicone rubber and the toner causes some of the toner pigment to become silicone. It may deposit on rubber, which may cause deterioration of gloss and ghost due to deposited images. Further, in this surface layer, when a toner of a type containing a release agent such as wax is used as the toner, such a release agent has a good compatibility with the silicone rubber, and therefore such a release agent is used on the surface. The release agent is likely to remain in the layer, and the release agent may contaminate the surface of the photosensitive drum in the image forming unit.

Another example is a surface layer made of a fluororesin. In this surface layer, the property of easily repelling the toner and the release agent contained therein is obtained, so that the deposition of the toner pigment on the surface layer and the residual release agent do not occur, but there is no elasticity and the physical properties are relatively hard. Therefore, there is a problem that the adhesiveness to the recording paper at the time of transfer and fixing is poor.
It is also possible to provide a rubber layer below this fluororesin layer to form a double-structured surface layer, but in this case, the fluororesin layer on the surface side deforms (moves) the rubber layer on the lower side. The surface may be cracked because it cannot follow.

Another example is a surface layer formed of a silicone resin. In this surface layer, toner pigment may be deposited or the surface may be cracked. It is also possible to form the surface layer by using a material in which a fluororesin is added as an additive to silicone rubber. In this case, however, the fluororesin component does not uniformly appear on the surface, so that a toner or a release agent is not applied. The property of being difficult to repel cannot be obtained, and the additive for the fluororesin may be missing.

Further, a surface layer formed of a specific fluororubber containing perfluoropolyether in the main chain can be mentioned. This particular fluororubber is a material that has the excellent properties of silicone rubber and fluororubber. Since this surface layer has elasticity equivalent to that of silicone rubber, good adhesion to the recording paper of the intermediate transfer belt can be obtained, and cracks do not occur on the surface. Further, since the toner and the release agent contained therein are easily repelled by the fluorine component, deposition of the toner pigment and residual release agent do not occur. From this, it is recognized that this surface layer is most suitable as the surface layer of the intermediate transfer belt.

[0009]

By the way, in such an image forming apparatus, as the number of times the image is formed (the number of prints, etc.) increases, the intermediate transfer belt 200 is subjected to stress due to contact of the recording paper and heating process. After that, the adhesive force with the toner increases, and eventually the toner image carried on the intermediate transfer belt cannot be completely transferred to the recording paper and remains on the intermediate transfer belt, resulting in image offset or white There is a problem of causing image defects called omission.

In order to increase the adhesive force of the intermediate transfer belt with the toner, the intermediate transfer belt having the surface layer made of the above specific fluororubber was used, and the toner containing the releasing agent was used as the toner. Even in such a case, due to the characteristic that the surface layer easily repels the release agent, the release effect of the release agent is not effectively exerted, and the paper dust of the recording paper adheres to the surface layer. Therefore, it will occur.

Therefore, as a measure for preventing such an increase in the toner adhesion force of the intermediate transfer belt, it is effective to employ a means for applying silicone oil as a release agent to the surface of the intermediate transfer belt. (For example, JP-A-5
-107950).

However, in this case, particularly when the intermediate transfer belt is an unused (new) one, the toner adhesion force during the image formation of several hundreds to several thousands after the start of its use. Cannot be effectively prevented from rising (Fig.
However, when rough paper (paper with a relatively rough surface) such as embossed paper, drawing paper, certificate paper, etc. is used, there is a problem that white spots occur. This phenomenon remarkably occurs even when an intermediate transfer belt having a surface layer made of the above specific fluororubber is used. This is presumed to be due to the fact that the silicone oil is easily repelled due to the characteristics of the particular fluororubber due to the fluorine component, and it is particularly difficult for the silicone oil to repel the surface layer at the initial stage of use.

It is considered effective to apply a large amount of the silicone oil from the viewpoint of surely preventing the toner adhesion force from increasing in the initial stage of use of the intermediate transfer belt. In this case, there is a problem that the surface of the photosensitive drum in the image forming unit is contaminated by such silicone oil, and a fogging phenomenon or oil streaks occur on the drum surface, resulting in deterioration of image quality.

Incidentally, as a measure for preventing oil adhesion and contamination on the surface of the photosensitive drum, a means for adjusting the application timing by providing a roll member for applying silicone oil so that it can be brought into contact with and separated from the surface of the intermediate transfer belt (for example, (Kaihei 11-212379) or a means for forming a toner layer in an excessive oil adhering region of the intermediate transfer belt and removing the toner layer together with the toner by a cleaning device (for example, Japanese Unexamined Patent Application Publication No. 2-212058)
000-66533) may be applied. However, all of these measures are effective measures against oil adhesion contamination on the surface of the photosensitive drum, but as described above, the toner adhesion force increases at the initial stage of use of the new intermediate transfer belt, and It is not possible to prevent the occurrence of blank areas on the paper.

As another measure, means for forming a film by ejecting a liquid having ink repellency onto the intermediate transfer belt and then curing it by heat or the like (Japanese Patent Laid-Open No. 2000-108334).
It is conceivable to apply the Japanese patent publication). However, in the case of this measure, there are problems that it is difficult to form a uniform film due to unevenness of jetting, the film forming apparatus becomes complicated, and the cost increases.

In addition to the above, according to the research conducted by the present inventors, the problem of the image defect such as the image offset or the white spot as described above is solved by, for example, heating and pressurizing the toner image on the recording sheet by using the fixing belt. It has been confirmed that even in an image forming apparatus having a fixing device that performs the above fixing, the adhesion force of the fixing belt to the toner increases at the initial stage of use, and the same occurs. In order to prevent the adhesion force from increasing, it is effective to apply silicone oil to the surface of the fixing belt. In that case, the excess oil applied to the fixing belt is transferred to the recording paper and There are problems such as surface gloss and difficulty in writing characters on paper.

Further, in order to mainly suppress the following blisters, even in an image forming apparatus provided with a fixing auxiliary belt which comes into contact with and rotates in a predetermined section of the intermediate transfer belt or the fixing belt described above, It has also been confirmed that the increase in the adhesive force with the toner in the initial stage of use may cause the above-mentioned image defects such as image offset or white spots. The blister means that the moisture contained in the recording paper evaporates into a vapor under heating and high temperature at the time of the transfer fixing or the fixing by the fixing belt, and the vapor enters between the recording paper and the toner image (layer). This is an image quality defect in which the toner image fixed on the sheet appears to float.

The present invention has been made in view of the above circumstances, and its main purpose is to provide an image carrier for carrying a toner image, a fixing belt for fixing the toner image on a recording sheet, and the like. As an image forming apparatus that has a release agent applied to the surface of the image bearing member, the fixing belt, etc. at the stage of use to ensure releasability for toner, etc., it causes contamination by the application of the release agent. In particular, to provide an image forming apparatus capable of suppressing the adhesive force to toner at the initial stage of use (the stage when the unused one is first used) of the surface of the image bearing member, the fixing belt and the like. is there.

[0019]

SUMMARY OF THE INVENTION The present invention (first invention) capable of solving the above-mentioned problems includes an image carrier which carries a toner image on its surface and rotates, and a toner image on the image carrier. Transfer fixing means for transferring and fixing at least heat and pressure on recording paper supplied so as to come into contact with the surface of the image carrier, and a release agent for applying a first release agent on the surface of the image carrier. In the image forming apparatus having a coating unit, the image carrier has a mold release pretreatment in which the second mold release agent is applied to the surface of the image carrier and the contact member is brought into contact with the contact member at least in an unused stage. It is characterized by being applied.

The mold release pretreatment is either a treatment performed before mounting the image carrier on the image forming apparatus, or a treatment performed after mounting the image carrier at an unused stage. In the case of the former process, it may be carried out by incorporating it as one of the manufacturing steps of the image bearing member. In this case, the processing apparatus (equipment) used for performing the mold release pretreatment is used. On the other hand, in the case of the latter processing, it suffices to install a mold release processing means capable of performing mold release pre-treatment as described later in the image forming apparatus. The unused stage is a stage in which the image carrier has never been used in an actual image forming operation. Further, at least the unused stage is meant to include not only the unused stage but also stages subsequent to the actual image forming operation.

As the second release agent applied to the pre-release treatment, the same one as the first release agent applied by the release agent applying means is usually used, but a different one is used if necessary. It doesn't matter. As the second release agent and the first release agent,
Any material can be used as long as it can impart releasability to the toner to the image carrier without hindering image formation, and specific examples thereof include polyethylene wax, carnauba wax, fluorine oil and silicone oil. Dimethyl silicone oil is preferable from the viewpoint of ease of handling and the like, which does not require a step of heating and melting the mold. Further, the coating amount of the release agent at the time of this treatment is not particularly limited, but for example, it is preferably about 0.2 μl per A4 size sheet.

The contact member can uniformly contact the surface of the image bearing member coated with the second release agent and spread the second releasing agent on the surface of the image bearing member. Any member can be used, and a roll-shaped member is preferable. In addition, when dimethyl silicone oil is used as the second release agent, this contact member promotes the coating efficiency of the release agent and more effectively obtains the function and effect described later by the release pretreatment. From the viewpoint, the contact angle of the contact member with dimethyl silicone oil is 20 °.
It is preferable to be composed of the following materials. further,
The temperature of the image carrier contacting the contact member is preferably 50 ° C. or higher, more preferably 160 ° C. or higher.
℃ or above. Although this heating may be performed by installing a dedicated heating means, it may be performed by using the heating portion of the transfer fixing means.

An image carrier which has been subjected to such a release pretreatment at least in an unused stage has an initial stage of use (for example, the first several thousand images) compared to the case where the release pretreatment is not performed. The increase in the adhesive force of the image carrier to the toner in the step of forming) is suppressed. Figure 1
The state of the adhesive force when the release agent coating process is performed by the release agent treatment and the state of the adhesive force in the initial stage of use after the process are schematically shown. The two-dot chain line shows the adhesive force when the pre-mold release treatment is not performed. That is, as shown in the figure, the increase in the adhesive force in the initial stage of use is suppressed (the inclination of the adhesive force becomes gentle). This makes it possible to reduce the occurrence of image defects such as image offset and white spots in the initial stage of use. In addition, since it is not necessary to increase the coating amount of the first release agent in the initial stage of use, the problem of contamination due to excessive coating of the release agent can be avoided. In addition, it is preferable that the pre-release treatment is finally performed so that the contact angle of the surface of the image bearing member with the dimethyl silicone oil after the treatment is 15 ° or less.

Further, in this pre-release treatment, since the contact member is brought into contact with the surface of the image carrier on which the second release agent has been applied, the release agent is applied efficiently in a short time. Will be able to. In particular, when the portion of the image carrier that contacts the contact member is heated to the temperature as described above, the coating efficiency of the second release agent on the image carrier by the contact member is further promoted. In particular, when heated to 160 ° C. or higher, the coating efficiency of the release agent can be promoted regardless of the material of the surface of the contact member.

In the image forming apparatus according to the first aspect of the present invention, there are provided an application means for applying the second release agent to at least the unused stage surface of the image carrier and an abutting member for abutting the application surface. A mold release treatment means may be provided, and at least the mold release pretreatment may be performed by this mold release treatment means.

When the second release agent to be applied is the same as the first release agent, the release processing means releases the release agent applying means to apply the first release agent. It can be configured so that it is also used as a means.

When such a mold release processing means is installed in the image forming apparatus, the mold release pretreatment for the unused image carrier can be performed in the image forming apparatus by the mold release processing means. it can. This eliminates the need for a process (work) for performing the mold release pretreatment in the image carrier manufacturing stage, thus eliminating the need for a processing device (equipment) used for performing the mold release pretreatment in the manufacturing stage. .

The release pretreatment should be performed as a treatment for simultaneously adhering to the toner image on the surface of the image bearing member before or at the same time as applying the second releasing agent. Is desirable. The adhesive force increasing process can be realized by, for example, bringing a blank recording sheet into contact with the surface of the image carrier at an unused stage, but the process content is not particularly limited.

The adhesive force with respect to the toner image (toner) is measured by an adhesive force measuring method and apparatus described later. Further, the increase of the adhesive force may be the case where it is larger than the adhesive force before the increasing process,
From the viewpoint of more effectively obtaining the effect of this increasing process, it is preferable that the adhesive force obtained by the measuring method described in the following embodiment be 0.5 N or more.

When such an adhesive force increasing process is performed during the mold release pretreatment, compared with the case of the mold releasing pretreatment in which the adhesive force increase process is not performed, the image carrier is particularly used at the initial stage of use. The increase in the adhesive force to the toner is further suppressed. The state of the adhesive force when the adhesive force increasing process is performed by the release agent process is also schematically shown in FIG. As shown in the figure, the adhesive force rises once and the adhesive force once rises, but the release agent application process reduces the adhesive force, and eventually the increase in adhesive force is suppressed in the initial stage of use. Become so.

Here, the image carrier is capable of carrying and rotating a toner image, and specifically, is an intermediate transfer belt in the form of a belt, a photosensitive belt, or the like. The image bearing member (image bearing belt) preferably has a structure in which a surface layer having releasability for a toner image is formed. The surface layer is formed of, for example, a material such as silicone rubber, fluororesin, or silicone resin, but is preferably formed of a specific fluororubber containing perfluoropolyether in the main chain described above. . The recording paper may be any recording medium that can transfer and fix a toner image and can be handled by the image forming apparatus, and the type and the like thereof are not particularly limited.

The transfer / fixing means is provided with a heating section for heating the toner image on the image carrier and a pressure section for applying pressure to bring the recording paper into close contact with the image carrier carrying the toner image. It is preferably one. The heating unit and the pressure unit may be arranged at the same position with respect to the image carrier, or may be arranged at different (distant) positions (the heating unit is the pressure unit). (Arranged on the upstream side in the rotation direction of the image carrier). Further, when the image carrier is in the form of a belt, the transfer / fixing unit includes a cooling unit that cools the recording paper and the toner image between the pressing unit and the peeling unit that separates the recording paper from the image carrier. (Cooling means) may be installed.

The above-mentioned releasing agent applying means is not particularly limited in the constitution such as the applying method as long as it can uniformly apply the first releasing agent to the surface of the image bearing member. When dimethyl silicone oil is applied as the first release agent, the amount applied to the image bearing member is preferably 0.15 μl or less per A4 size recording sheet. Since the image carrier is subjected to the release pretreatment as described above, the increase in the adhesive force to the toner at the initial stage of use is suppressed, so that it is necessary to increase the amount of release oil applied during image formation. As a result, it is possible to prevent the occurrence of oil streaks on the surface of the photosensitive drum or the like of the image forming unit due to excessive application of oil to the image bearing member, thereby inducing deterioration of image quality.

Further, it is preferable that the releasing agent applying means is provided with an abutting member for abutting the application surface of the image carrier on which the first releasing agent is applied. When this abutting member is installed, the coating efficiency of the first release agent can be increased and the coating amount can be reduced. In addition, in the case where dimethyl silicone oil is used as the first release agent, this contact member can promote the coating efficiency of the release agent, and the like. Is preferably made of a material having a contact angle with dimethyl silicone oil of 20 ° or less. Further, the image carrier which comes into contact with the contact member may be heated so that the temperature at the time of contact is preferably 50 ° C. or higher. The heating may be performed by installing a dedicated heating means,
The heating unit of the transfer fixing unit may be used. By heating in this way, the coating efficiency of the first release agent applied to the image carrier by the contact member is further promoted. Further, the contact member is arranged so as to contact and separate from the image carrier only when necessary in accordance with the application timing of the first release agent, and apart from the image carrier at other times. Of course, this contacting / separating installation is indispensable especially when the contact member is installed in the section of the image carrier on which the toner image is carried.

Next, according to the present invention (second invention) capable of solving the above-mentioned problems, the recording paper carrying the toner image to be fixed is supplied so as to come into contact with the surface of the rotating fixing belt, and at least heating and In an image forming apparatus having a fixing unit that applies pressure to fix the toner image on a recording sheet, and a releasing agent applying unit that applies a first releasing agent to the surface of the fixing belt of the fixing unit, the fixing belt is At least in an unused stage, the mold release pretreatment for applying the second release agent to the surface and contacting the contact member with the application surface is performed.

The fixing means has a rotating fixing belt, and a heating portion for heating the toner image on the recording paper supplied so as to come into contact with the surface of the fixing belt, and the recording paper is brought into close contact with the fixing belt. It is preferable to provide a pressurizing unit for applying such pressure. The heating unit and the pressing unit may be arranged at the same position with respect to the fixing belt, or may be arranged at different (distant) positions (the heating unit is the pressing unit). (Disposed upstream of the fixing belt in the rotation direction). The fixing belt has substantially the same structure as the belt-shaped image carrier in the first aspect of the invention, and particularly preferably has a structure in which a surface layer made of the above-mentioned material is formed.

The first aspect of the image forming apparatus of the second invention
The release agent, the release agent applying means, the unused stage, the second release agent, the release pretreatment, and other elements, and the constituents related to these elements are the same as those used in the first invention. The content is basically the same as each element.

The fixing belt which has been subjected to such release pretreatment at least in an unused stage is in an initial stage of use (for example, the first several thousand sheets of image formation) as compared with the case where the release pretreatment is not performed. The increase of the adhesion force of the fixing belt to the toner in the step (FIG. 1) is suppressed (see FIG. 1).
reference). This makes it possible to reduce the occurrence of image defects such as image offset and white spots in the initial stage of use. In addition, since it is not necessary to increase the coating amount of the first release agent in the initial stage of use, problems such as occurrence of paper shining and deterioration of character writing suitability due to such excess release agent coating are avoided. Will be done. Further, in this pre-release treatment, since the abutting member is brought into contact with the application surface on which the second release agent is applied to the fixing belt, the release agent can be applied efficiently in a short time. become.

In the image forming apparatus according to the second aspect of the invention, the fixing belt is provided with the second surface with respect to at least the unused surface.
It is possible to provide a mold release processing means including a coating means for applying a mold release agent and a contact member for contacting the coating surface, and to perform at least the mold release pretreatment by the mold release processing means. it can. When the second release agent to be applied is the same as the first release agent, the release processing means uses the release agent applying means to apply the first release agent as the release processing means. It is also possible to configure so as to be used also.

When such a mold release processing means is installed in the image forming apparatus, the mold release pretreatment for the unused fixing belt can be performed in the image forming apparatus by the mold release processing means. . This eliminates the need for a process (work) for performing the mold release pretreatment in the manufacturing stage of the fixing belt, so that a processing device (equipment) used for performing the mold release pretreatment in the manufacturing stage is also unnecessary.

The release pretreatment in the second aspect of the present invention is a treatment for simultaneously performing an adhesion increasing process for increasing the adhesion of the surface of the fixing belt to the toner image before or at the same time as applying the second release agent. It is desirable to configure.
This adhesion increasing process can be realized by, for example, bringing a blank recording sheet into contact with the surface of the fixing belt in an unused stage, but the process content is not particularly limited. The adhesive force with respect to the toner image is measured by the adhesive force measuring method and device described later, as in the case of the first invention. Further, the increase of the adhesive force may be a case where the adhesive force before the ascending process is increased, but from the viewpoint of more effectively obtaining the effect of the ascending process, the above measuring method is used. The resulting adhesion is 0.
The increase is preferably 5 N or more.

When such an adhesive force increasing process is performed in the mold releasing pretreatment, as compared with the case of the mold releasing pretreatment in which the adhesive force increasing process is not performed, especially in the fixing belt in the initial stage of use. The increase of the adhesive force to the toner is further suppressed.

Next, according to the present invention (third invention) capable of solving the above-mentioned problems, an image bearing member carrying a toner image on its surface and rotating, and a toner image on this image bearing member are provided. A transfer fixing means for transferring and fixing the recording paper by heating and pressing at least to the recording paper supplied so as to come into contact with the surface of the recording medium, and a surface portion between the transfer fixing position of the image carrier and the recording paper separating position. An image forming apparatus comprising: a fixing auxiliary belt that rotates in contact with the image carrier; and a release agent applying unit that applies a first release agent to each surface of the image carrier and the fixing auxiliary belt. The belt is
It is characterized in that at least in an unused stage, a mold release pretreatment for applying the second release agent to each surface and contacting the contact member to each application surface is performed.

As described above, the fixing auxiliary belt is rotated in contact with a predetermined section of the image carrier or the fixing belt, mainly for the purpose of suppressing blisters, as described above. Used in a heated environment. This fixing auxiliary belt has substantially the same structure as the fixing belt in the second invention, and particularly preferably has a structure in which a surface layer made of the material exemplified in the first invention is formed.

The first aspect of the image forming apparatus of the third aspect of the invention.
The release agent, the release agent applying means, the unused stage, the second release agent, the release pretreatment, and other elements, and the constituents related to these elements are the same as those used in the first invention. The content is basically the same as each element. The release agent applying means is usually composed of one for the image bearing member and one for the fixing auxiliary belt, but it has a configuration capable of simultaneously applying the first releasing agent to both the image bearing member and the fixing auxiliary belt. It can be one.

The image carrier and the fixing auxiliary belt which have been subjected to such pre-release treatment at least in the unused stage are in the initial stage of use (for example, several thousand at the beginning) as compared with the case where the pre-release treatment is not performed. It is possible to suppress an increase in the adhesive force of the image carrier and the fixing auxiliary belt with respect to the toner in the step of forming an image for one sheet (see FIG. 1). This makes it possible to reduce the occurrence of image defects such as image offset and white spots in the initial stage of use. Further, since it is not necessary to increase the amount of the first release agent applied to the image carrier and the fixing auxiliary belt in the initial stage of use, the excessive amount of the release agent applied causes the back surface of the paper to be shiny during double-sided image formation. Also, problems such as difficulty in writing characters can be avoided. Further, in this pre-release treatment, since the contact member is brought into contact with the application surface of the image carrier and the fixing auxiliary belt on which the second release agent is applied, the release agent is applied efficiently and in a short time. You will be able to.

In the image forming apparatus of the third invention, a coating means for coating the second release agent onto each surface of the image bearing member and the fixing auxiliary belt at least in an unused stage and abutting on each coating surface. It is possible to install a mold release processing means having a contact member for making it possible to perform at least the mold release pretreatment by this mold release processing means. When the second release agent to be applied is the same as the first release agent, the release processing means uses the release agent applying means to apply the first release agent as the release processing means. It is also possible to configure so as to be used also.

When such a mold release processing means is installed in the image forming apparatus, the mold release pretreatment for the unused image carrier and fixing auxiliary belt is performed in the image forming apparatus. Can be done by This allows
Since the process for performing the pre-mold release pretreatment is not required in the manufacturing stage of the image carrier and the fixing auxiliary belt, the processing device used for performing the pre-mold release pretreatment in the manufacturing stage is also unnecessary.

In the release pretreatment in the third aspect of the invention, an adhesion increasing treatment for increasing the adhesion of the surface of the image carrier and the fixing auxiliary belt to the toner image is applied before or simultaneously with the application of the second release agent. It is desirable that the processing is performed together. The content of the structure relating to the adhesion increasing process is the same as that of the first invention.

When such an adhesive force increasing process is carried out in the mold releasing pretreatment, compared with the case of the mold releasing pretreatment in which the adhesive force increasing process is not carried out, the image carrier is particularly in the initial stage of use. Also, the increase in the adhesive force of the fixing auxiliary belt to the toner is further suppressed (see FIG. 1).

Next, according to the present invention (fourth invention) capable of solving the above-mentioned problems, the recording paper carrying the toner image to be fixed is supplied so as to contact the surface of the rotating fixing belt, and at least heating and A fixing unit that pressurizes and fixes the toner image on the recording sheet; a fixing auxiliary belt that rotates by contacting a surface portion between the fixing position and the recording sheet separating position of the fixing belt of the fixing unit; In an image forming apparatus having a release agent applying means for applying a first release agent to each surface of the carrier and the fixing auxiliary belt, the fixing belt and the fixing auxiliary belt are at least in an unused stage,
The second release agent is applied to each of the surfaces, and a release pretreatment for bringing the abutting member into contact with each of the applied surfaces is performed.

Concerning the contents of construction relating to the above-mentioned fixing device and fixing auxiliary belt, the fixing device and the third fixing device in the second invention are described.
It is the same as the fixing auxiliary belt in the invention. Also,
Concerning the respective elements such as the first release agent, the release agent applying means, the unused stage, the second release agent, the release pretreatment, etc. in the image forming apparatus of the fourth aspect of the invention, and the constitutional contents related to these elements. Has basically the same contents as the above-mentioned elements used in the first invention and the third invention.

The fixing belt and the auxiliary fixing belt which have been subjected to such a release pretreatment at least in an unused stage are in the initial stage of use (for example, the first several thousand sheets) as compared with the case where the release pretreatment is not performed. The increase in the adhesive force of the fixing belt and the fixing auxiliary belt to the toner in the step of forming an image) is suppressed (see FIG. 1). This makes it possible to reduce the occurrence of image defects such as image offset and white spots in the initial stage of use. Also,
Since it is not necessary to increase the amount of the first release agent applied to the fixing belt and the auxiliary fixing belt in the initial stage of use, the application of such a large amount of release agent causes a problem such as the occurrence of shining on the paper and the difficulty of writing characters. Will also be avoided. Further, in this pre-release treatment, the contact member is brought into contact with the application surface of the fixing belt and the auxiliary fixing belt on which the second release agent is applied, so that the release agent is applied efficiently and in a short time. Will be able to.

In the image forming apparatus according to the fourth aspect of the present invention, a coating means for coating the second release agent on the surfaces of the fixing belt and the auxiliary fixing belt at least in the unused stage and the coating surfaces thereof are brought into contact with each other. It is possible to install mold release processing means including a contact member, and to perform at least the mold release pretreatment by the mold release processing means. When the second release agent to be applied is the same as the first release agent, the release processing means uses the release agent applying means to apply the first release agent as the release processing means. It is also possible to configure so as to be used also.

When such a mold release processing means is installed in the image forming apparatus, the mold release pretreatment for the unused fixing belt and fixing auxiliary belt is performed by the mold release processing means in the image forming apparatus. It can be carried out. This eliminates the need for a process for performing the pre-mold release treatment at the manufacturing stage of the fixing belt and the auxiliary fixing belt, so that the processing device used for performing the pre-mold release treatment at the manufacturing stage is also unnecessary.

In the release pretreatment in the fourth aspect of the present invention, the adhesion pretreatment for increasing the adhesion to the toner image on the surfaces of the fixing belt and the fixing auxiliary belt is also performed before or simultaneously with the application of the second releasing agent. It is desirable to configure it as a process to be performed. The content of the structure relating to the adhesion increasing process is the same as that of the first invention.

When such an adhesive force increasing process is performed in the mold releasing pretreatment, compared with the case of the mold releasing pretreatment in which the adhesive force increasing process is not performed, the fixing belt and The increase of the adhesion force of the fixing auxiliary belt to the toner is further suppressed (see FIG. 1).

[0058]

BEST MODE FOR CARRYING OUT THE INVENTION [First Embodiment] FIG. 2 shows a main part of a color image forming apparatus 1A according to a first embodiment of the present invention.

<Basic Structure of Image Forming Apparatus> This color image forming apparatus 1A has a color component of yellow (Y), magenta (M), cyan (C) and black (K) based on image information by an electrophotographic method. Four image forming units 10Y, 10M, 10C and 10K which respectively form toner images
And the image forming units 10Y, 10M, 10C, 10
An intermediate transfer belt 20 to which each toner image formed by K is transferred, and a transfer fixing device 30 that transfers and fixes the toner image on the intermediate transfer belt 20 onto the recording paper P.
And a release agent coating device 4 for coating the surface of the intermediate transfer belt 20 with a release agent for imparting a releasing property to the toner image.
It is basically composed of 0 and. The one-dot chain line with an arrow in the figure shows the conveyance path of the recording paper P. The recording papers P are supplied one by one from a paper supply unit (not shown). As the toner, a wax-containing toner is used.

Image forming units 10Y, 10M, 10
C and 10K are arranged in a parallel state at regular intervals along the horizontal direction, and both have the same configuration. That is, each of the image forming units 10 is, as shown in FIG. 3, a photosensitive drum 11 that rotates at a predetermined speed in the direction of arrow A by a rotary drive source (not shown).
And a charging device 12 that uniformly charges the surface of the photosensitive drum 11, and based on image information input to the surface of the photosensitive drum 11 charged by the charging device 12 from a document reading device, an external connection device, or the like. A latent image forming device 13 that forms an electrostatic latent image by exposing light H emitted from a semiconductor laser, a light emitting diode, or the like, and an electrostatic latent image on the photosensitive drum 11 formed by the latent image forming device 13. A developing device 14 that supplies toner (developer) of a predetermined color to develop the image, a primary transfer device 15 that electrostatically transfers the toner image on the photosensitive drum 1 to the intermediate transfer belt 20, and a photosensitive drum. The drum cleaner 16 that removes and cleans the adhering substances on the surface of No. 1 constitutes its main part.

The intermediate transfer belt 20 is driven by a drive roll 23 which is rotationally driven by a rotary drive source (not shown) and a plurality of support rolls 24a to 24a which are driven to rotate to support the belt 20.
4f, 25 etc., and the drive roll 2
3 and the support roll 24a are arranged so as to pass the transfer position of the photosensitive drum 11 in each of the image forming units 10. The intermediate transfer belt 20 is rotated in the arrow B direction by the drive roll 23. The supporting roll 24c is a roll having a relatively small diameter, and is used for the intermediate transfer belt 20 during transfer fixing.
It functions as a peeling roll for peeling the recording paper P from the paper.

As the intermediate transfer belt 20, as shown in FIG. 5, one having a two-layer structure in which a surface layer 22 is laminated on a belt base material 21 is used. The belt base material 21 is made of a heat-resistant material, and in this example, a polyimide film having a thickness of about 50 to 80 μm, which is made by containing carbon black and appropriately adjusting the volume resistivity, is used. is doing. The surface layer 22 is made of an elastic material from the viewpoint of ensuring good adhesion between the intermediate transfer belt 20 and the recording paper P with a toner image interposed during transfer and fixing. In this example, a layer having a thickness of about 50 to 150 μm is formed by coating and forming a specific fluororubber containing a perfluoropolyether on the main chain (SIFEL610-10 manufactured by Shin-Etsu Chemical Co., Ltd.).

The transfer / fixing device 30 includes transfer rolls 31 and 32 which are arranged to face each other with the intermediate transfer belt 20 sandwiched between the support rolls 24b and 24c.
The heating plate 36, which heats the toner image via the intermediate transfer belt 20 between the supporting rolls 24b and 24c, constitutes the main part.

Each of the transfer rolls 31 and 32 has a structure in which an elastic layer such as silicone rubber is laminated on the surface of a cylindrical metal roll, and an electrothermal heater is installed inside the metal roll. . This transfer roll 3
Nos. 1 and 32 are pressed so that a pressure contact portion (nip portion) having a predetermined width is formed while sandwiching the intermediate transfer belt 20, and the pressure at the pressure contact portion is about 0.003 to 0.005 Pa. It is installed in the state. The heating plate 36 is a heating means for heating the toner of the toner image carried on the intermediate transfer belt 20 (strictly speaking, the surface layer 22) to such an extent that it melts, and in this example, the inner circumference of the intermediate transfer belt 20. A structure is used in which a sheet-like electric heater is attached to the back surface of a metal plate arranged so as to face the surface. Therefore, in the transfer fixing device 30, the arrangement part of the heating plate 36 functions as a main heating part, and the transfer rolls 31, 32 are provided.
Functions as a pressurizing unit that also serves as an auxiliary heating unit.

The release agent applying device 40 is installed so as to contact the surface (surface layer 22) of the intermediate transfer belt 20 between the drive roll 23 and the image forming unit 10 (Y) to apply the release agent. A mold release agent coating roll 41 and a mold release maintaining roll 2 which is also a belt support roll installed so as to come into contact with the mold release agent coating surface coated by the mold release agent coating roll 41.
4e and 4e. The release agent coating roll 41 is one in which an elastic layer made of silicone rubber or the like is formed on the surface of a metal roll, and the elastic layer is impregnated with dimethyl silicone oil as a release agent (first release agent). . Further, the coating roll 41 is installed so as to be able to come into contact with and separate from the intermediate transfer belt 20 because, for example, the release agent is coated at a predetermined time. The mold release maintenance roll 24e is a metal roll made of aluminum or the like.

In addition, in the image forming apparatus 1A, the belt cleaning roll 38 for removing toner and the like adhering to the surface of the intermediate transfer belt 20 is opposed to the belt support roll 24d via the belt 20. It is arranged in.

The cleaning roll 38 has a structure in which a resin layer is formed on a hollow metal roll and a heat source is installed inside the roll.
The cleaning work is performed by heating the toner remaining on the top of the toner so that the toner is melted. Further, the cleaning roll 38 is pressed against the belt 20 after the rotation of the intermediate transfer belt 20 is started immediately after the rotation of the intermediate transfer belt 20 is started, and can be separated from the belt 20 immediately before the rotation is stopped. It is arranged. Further, the belt support roll 24d facing the cleaning roll 38 is also provided with a heating source (not shown) for heating the toner remaining on the intermediate transfer belt 20 to the extent of melting it.

Further, the transfer roll 31 is provided with a roll cleaning roll 33 for removing toner and the like adhering to the roll surface. The cleaning roll 31 has a structure in which a resin layer is formed on a hollow metal roll and a heat source is installed inside the roll. Further, like the cleaning roll 38, the cleaning roll 33 also contacts the belt 20 after the rotation thereof is started in order to reduce the load applied immediately after the rotation of the intermediate transfer belt 20 is started.
It is arranged so as to be able to come into contact with and separate from it.

As will be described later, the image forming apparatus 1A is configured to use, as the intermediate transfer belt 20, the intermediate transfer belt 20 which has been subjected to the pre-release processing at least in its unused stage.

<Operation During Image Formation> In the color image forming apparatus 1A having such a basic structure, a color image is formed as follows.

First, in each image forming unit 10, the rotating photosensitive drum 11 is uniformly charged by the charging device 12 so as to have a desired charging potential, and then the charged surface is colored by the latent image forming device 13. By scanning and exposing light (for example, a laser beam) H corresponding to the decomposed image data, an electrostatic latent image having a desired latent image potential is formed. Thereafter, the latent image is supplied from the developing device 14. It is developed with the toner of the corresponding color. By repeating this image forming process in each image forming unit 10 in the same manner,
On each photosensitive drum 11, yellow, magenta, cyan,
Toner images of four black colors are individually formed. The four-color toner images formed on the respective photosensitive drums 11 are sequentially primary-transferred so as to be superimposed on the surface of the intermediate transfer belt 20 by the electrostatic transfer action of the transfer device 15 in the primary transfer portion. The surface of the photosensitive drum 11 after the transfer is cleaned by the drum cleaner 16.

The toner image transferred to and carried on the intermediate transfer belt 20 is conveyed so as to pass through the transfer fixing device 30 as the belt rotates, so that the recording paper P is recorded.
It is transferred and fixed on. That is, the toner image on the intermediate transfer belt 20 is heated and appropriately melted when passing through the heating plate 36, and then the intermediate transfer belt 20 and the transfer roll 3 are melted.
In the state of being in contact with the recording paper P supplied during 1 (press contact portion), the recording paper P is heated and pressed together with the recording paper P. As a result, the toner image is secondarily transferred and fixed on the recording paper P.

The recording paper P on which the toner image is transferred and fixed is
The intermediate transfer belt 20 is conveyed to a peeling position where the supporting roll 24c as a peeling roll exists in a state of being in close contact with the outer peripheral surface of the intermediate transfer belt 20, and is cooled in this process. By this cooling, the heated and melted toner is sufficiently aggregated and solidified, and a strong adhesive force is generated between the toner and the recording paper P, so that the toner is strongly fixed on the paper. The recording paper P cooled in this way is peeled off by itself from the intermediate transfer belt 20 which bends and runs with a small radius of curvature at the peeling position where the support roll 24c is present.

As a result, a full-color image is formed on one side of the recording paper P. At this time, the image formed of the toner formed on the recording paper P has a rich glossiness because the surface smoothness of the intermediate transfer belt 20 is directly transferred to the image surface.

Further, during such image formation,
Dimethyl silicone oil is applied to the surface of the intermediate transfer belt 20 from the release agent applying roll 41 at a predetermined interval, thereby imparting releasability to the toner of the intermediate transfer belt 20 at the time of secondary transfer or the like.

The surface of the intermediate transfer belt 20 after the recording paper P is peeled off is cleaned by the cleaning roll 38. At this time, the toner adhering to the intermediate transfer belt 20 is cooled as described above, but the support roll 2
The cleaning roll (resin layer of the cleaning roll) 38 is melted again by the heating action of 4d and the adhesive force with the belt is reduced.
Are transferred to and removed.

Further, in the image forming apparatus 1A, since the intermediate transfer belt 20 having the surface layer 22 made of the specific fluororubber is used, the photosensitive drum of the toner image is formed by viscoelasticity of the silicone rubber. While the transferability from 11 to the intermediate transfer belt 20 is secured,
Transferability of the molten toner onto the recording paper P is ensured due to the releasing property of the fluororubber. As a result, particularly when compared with an intermediate transfer belt having a surface layer made of silicone rubber, an image with a rich glossiness can be obtained without deterioration of image gloss.

<Test and Consideration Concerning Toner Adhesiveness of Intermediate Transfer Belt> The present invention has been completed in consideration of various tests and consideration conducted using the image forming apparatus 1A according to the first embodiment. The process will be described.

FIG. 30 shows a white spot (image defect) at the time of running test by the image forming apparatus 1A of this example.
It shows the result of examining the occurrence situation of. This running test was performed using an unused intermediate transfer belt 20 while applying dimethyl silicone oil from the release agent applying roll 38 to the surface of the intermediate transfer belt 20. Details of the test conditions at this time are as follows.

As the intermediate transfer belt 20, a belt base material 21 made of a polyimide film and having a thickness of about 50 μm is used.
The surface layer 22 made of the specific fluororubber and having a thickness of about 80 μm was formed (belt width 320 mm, belt total length 2100 mm). As the toner, a toner containing a pigment and a wax made of polyethylene in a polyester resin (glass transition point: about 65 ° C., softening point: about 113 ° C.) was used. As the transfer rolls 31 and 32 of the transfer fixing device 30, rolls each having an outer diameter of about 50 mm were used, and the pressure load between the rolls was set to 765 N and the heating temperature was set to 95 ° C. The amount of dimethyl silicone oil applied at this time was 0.1 for A4 size paper.
It was set to be 5 μl.

Cleaning roll 33 of transfer roll 31
As the material, a metal roll on which a resin layer made of a polyester resin having substantially the same glass transition point and softening point as the base resin of the toner is formed is used, and the pressure load at the time of contact with the transfer roll 31 is used. 102N, heating temperature 11
It was set to 5 ° C. As the cleaning roll 48 of the intermediate transfer belt 20, a metal roll on which the same resin layer as that of the cleaning roll 33 is formed is used, and the pressing load applied to the intermediate transfer belt 20 (supporting roll 24c) is applied. The heating temperature was set to 204 N and the heating temperature was set to 120 ° C., which was slightly higher than the softening point of the toner. The heating temperature of the support roll 24c facing the cleaning roll 48 was set to 90 ° C.

With the image forming apparatus set under these conditions, a magenta solid toner image (density 2.25 g / m ² ) formed (printed) on the entire surface of the recording paper P was visually observed as a test image. The presence or absence of white spots in the obtained image and the amount thereof were examined and graded. Grade evaluation for white spots,
“Grade 0” was evaluated as a case where no white spots were generated, and “grades 1 to 5” was evaluated as a case where the amount of white spots was increased as the numerical value increased. Grades 1 and 5 are evaluated according to the following criteria. In this case, the acceptable grade was "1 or less". In addition, as the recording paper P, plain paper (manufactured by Fuji Xerox:
J paper) and rough paper (Fuji Xerox: rough paper 4024)
It was used. The running test was performed on about 40,000 sheets (40 kPV) of each of the recording sheets described above. At this time, printing was performed on eight recording sheets per revolution of the intermediate transfer belt 20. Grade 1: There is about 1 dropout / cm ² having a diameter of about 0.1 to 0.2 mm. Grade 5: omission diameter of approximately 1mm is 5 / cm ² or more.

From the results shown in FIG. 30, it was confirmed that almost no white spots were generated on the plain paper, while many white spots were generated on the rough paper, especially up to the first 5,000 sheets (5 kPV). It was confirmed to do.

Therefore, the following adhesion measurement test for examining the characteristics of the adhesion of the intermediate transfer belt 20 to the toner was conducted.

First, the adhesion of the intermediate transfer belt 20 to toner will be described. FIG. 5 shows the intermediate transfer belt 20.
FIG. 6 is a cross-sectional explanatory view schematically showing a state in which the upper melted toner Ta is transferred and fixed onto the recording paper P. In such a state, the adhesive force F1 generated between the molten toner Ta and the recording paper P, the intermediate transfer belt 20 and the molten toner Ta.
There are three forces acting, namely, the adhesive force F2 generated during the period and the cohesive force F3 inside the molten toner Ta. Then, the transfer and fixing of the toner is performed by peeling the molten toner Ta at the boundary with the intermediate transfer belt 20 without being divided when the recording paper P is peeled off from the intermediate transfer belt 20. In order to achieve this, it is necessary that the adhesive force F1 has a large force relationship with the adhesive force F2 and the cohesive force F3 inside the molten toner. Therefore, by measuring the force required for peeling the recording paper P from the intermediate transfer belt 20 in the above-described state, the intermediate transfer belt 20 and the molten toner Ta corresponding to the adhesive force of the intermediate transfer belt 20 to the toner are measured. It is possible to know the adhesive force F2 generated during the period.

From such a viewpoint, the intermediate transfer belt 20
The adhesive force to toner was measured using an adhesive force measuring device 2 as shown in FIG. 6a.

In this adhesive force measuring device 2, the transfer roll 32 and the belt supporting rolls 24b and 24c used in the image forming apparatus are installed in a state as shown in the drawing, and an intermediate transfer is performed on each of the rolls 32, 24b and 24c. The belt 20 is wound around, and the transfer roll 31 is arranged in a state of being pressed against the transfer roll 32 with the intermediate transfer belt 20 sandwiched therebetween. Further, the adhesive force measuring device 2 is provided with the heating plate 36 in a state of being in contact with the inner peripheral surface of the intermediate transfer belt 20 between the transfer roll 32 and the support roll 24c. The transfer rollers 31 and 32 both have an outer diameter of 48 mm.
Silicone rubber layer (hardness: 30 degrees) on 2 metal rolls
It is formed to have a thickness of mm, and an electric heater is installed inside the metal roll, and they are pressed against each other with a pressure load of 600N. The transfer roll 32 in this measuring device is connected to a rotary drive source and is also used as a drive roll.
Further, the adhesive force measuring device 2 pulls up the measurement recording paper PX conveyed by the belt 20 on the outer peripheral surface side of the intermediate transfer belt 20 on the heating plate 36 by pulling the recording paper PX upward (in the arrow direction). A tensile tester 3 is installed which is capable of peeling from 20 and measuring the peeling force at that time.

Then, measurement by the adhesive force measuring device 2
Around the intermediate transfer belt 20 to be measured
After setting the device, set the drive / transfer roll 32 to 152
℃, transfer roll 31 157 ℃, heating plate 36 115 ℃
To the intermediate transfer belt 20 after heating
Direction at a speed of 30 mm / sec. Then this
Transferring with the intermediate transfer belt 20 of the operating adhesive force measuring device 1
The recording paper PX for measurement is inserted between the rolls 32.
The recording paper PX for measurement has a size as shown in FIG. 6b.
15 mm x 60 mm coated paper (Fuji Xerox: J
25mm from the tip PXa of the coated paper) to the entire tip area
Cyan color toner layer (density 3.5g / m ²) Formed
It is a thing. This toner image is formed by applying the toner image to the photoreceptor.
Equipped with a function from forming to transfer to recording paper
Image forming apparatus.

After the recording paper PX for measurement inserted between the intermediate transfer belt 20 and the transfer roll 32 reaches the heating plate 36, the rotation of the intermediate transfer belt 20 is stopped, and after heating and leaving at that position for 1 minute. , The trailing edge P of the recording paper PX
Attach the hook of the tensile tester 2 to b and pull it upward (in the direction of the arrow) at a speed of 5 mm / sec. At this time, the average pulling force until the recording paper PX was completely peeled from the intermediate transfer belt 20 was measured, and the value was taken as the adhesive force of the intermediate transfer belt 20 to the toner.

The adhesion of the intermediate transfer belt 20 to the toner was measured by the following two types.

First, as described above, rough paper, which is likely to cause white spots in the initial stage of use, is used as the recording paper P, and a running test by the image forming apparatus is performed while forming a test toner image on a part thereof. When the process is repeated, the non-image portion of the recording paper P of the intermediate transfer belt 20 directly contacts and passes through, and the image portion of the recording paper P directly contacts the belt region (white background portion of the paper). The adhesive force to the belt region (paper passing patch portion) passing through the belt was measured by the adhesive force measuring device 2. In this running test, the release agent was not applied from the release agent applying device 40 to the intermediate transfer belt 20. In addition, the measurement of the adhesive force is performed by using the unused intermediate transfer belt 20.
And 2500 sheets, 5000 sheets, 27 sheets
When 000 sheets were printed, the intermediate transfer belt 20 used until then was transferred from the image forming apparatus to the adhesive force measuring apparatus 1 once each time. Then, the adhesive force was measured for the white paper passing portion and the paper passing patch portion of the intermediate transfer belt 20. The measurement result is shown in FIG.

From the results shown in FIG. 7, the intermediate transfer belt 20
It can be seen that the adhesive force in the paper passing blank area, that is, in the belt area where the recording paper P directly contacts without interposing the toner image, is significantly increased as compared with the paper passing patch area.
This is because paper dust adheres to the belt surface due to contact with the recording paper in the white area and the releasability from the toner deteriorates. It is presumed that this is because the deterioration of moldability is suppressed to some extent.

Next, a running test was conducted while applying a release agent, dimel silicone oil, to the entire surface of the intermediate transfer belt 20 including the white paper passing portion, and a running test was performed at that time. The adhesive force at each part was measured by the adhesive force measuring device 1. The measurement result is shown in FIG.

From the results shown in FIG. 8, the intermediate transfer belt 20
It can be understood that the increase in the adhesive force of the paper passing white background portion can be significantly reduced by applying the dimel silicone oil (oil supply). However, it has been found that even when this dimel silicone oil is applied, the adhesive force once increases in the initial printing operation up to about 5,000 sheets (5 kPV). This is because the specific fluororubber constituting the surface layer 22 of the intermediate transfer belt 20 has a property of easily repelling the dimel silicone oil, and the surface layer 22 of the intermediate transfer belt is sufficiently dusted at the initial stage of applying the oil. Therefore, it is presumed that the reason is that good releasability for the toner is not given.

Subsequently, the running test was carried out to check the occurrence of white spots, and the adhesive force of the white background portion of the intermediate transfer belt at each time point was checked. The measurement result is shown in FIG.

From the results shown in FIG. 9, there is a certain degree of correlation between the adhesive force and the white spot grade, and it seems that reducing the adhesive force is effective for reducing the occurrence of white spots. I understand. And, in order to bring this whiteout grade to an allowable level of "1 or less", the adhesive force is about 0.13.
It can be predicted that it is necessary to suppress the following.

From the above-mentioned measurement results, the present inventors have found that in order to reduce the occurrence of white spots at the time of printing up to around the first 5,000 sheets (5 kPV), an unused intermediate transfer belt is used. Focusing on the importance of how quickly a good release property for toner can be provided by applying a release agent (dimel silicone oil or the like) to No. 20, the following tests were continued.

First, various tests concerning the effect of applying the release agent are carried out by using an independent release agent applying apparatus 4 for applying the release agent to the unused intermediate transfer belt 20 as shown in FIG. went.

The apparatus 4 exclusively for applying the release agent is composed of the transfer roller 32 and the belt supporting roller 24 in the image forming apparatus 1A.
b and 24c are installed in a state as shown in the drawing, the intermediate transfer belt 20 is wound around the rolls 32, 24b and 24c, and then the intermediate transfer belt 20 is sandwiched and used in the release agent coating device 40. The release agent applying roll 41 is placed in pressure contact with the transfer roll 31, and the release maintaining roll 24e, which is also used in the release agent applying device 40, contacts the transfer roll 32 with the intermediate transfer belt 20 interposed therebetween. It is arranged in the state where it is made. In addition, the device 4 for exclusive use of the release agent coating includes the transfer roll 32 and the support rolls 24b and 24b.
The heating plates 36 are installed so as to be in contact with the respective inner peripheral surfaces of the intermediate transfer belt 20 between c.

The transfer roll 32 is the same as the transfer roll 32 in the adhesive force measuring device 2 described above, and also serves as a drive roll. The release agent coating roll 41 is the same as that in the release agent coating device 40, and the silicone rubber layer thereof is impregnated with dimethyl silicone oil. Also, as the release maintaining roll 24e, basically the same one as the release agent applying device 40 (a metal roll made of aluminum) is used. The release agent coating roll 41 and the release maintaining roll 24e are in pressure contact with the transfer roll 32 under a pressure load of 100 N and 600 N, respectively.

The release agent coating device 4 is used to apply the release agent after the unused intermediate transfer belt 20 is rotated to set the device, and then the drive / transfer roll 32,
The release agent coating roll 41 and the release maintaining roll 24e are both heated to 135 ° C., and the two heating plates 36 are both heated to 135 ° C. In this state, the intermediate transfer belt 2
0 is rotated in the direction of the arrow at a speed of 260 mm / sec.
As a result, dimethyl silicone oil is applied from the release agent applying roll 41 to the intermediate transfer belt 20 at a rate of 0.15 μl / A4 size sheet. The release agent applied in this way is leveled on the belt surface by passing through the release maintaining roll 24e.

Here, the difference in the effect of applying the release agent by changing the surface material of the release maintaining roll 24e was examined.

FIG. 11 shows an evaluation device 5 for evaluating the difference in the release agent coating effect depending on the surface material.
This evaluation device 5 is the same as the release agent application device 4 except that the belt support rolls 24b and 24c and the two heating plates 3 are used.
6 is omitted and the intermediate transfer belt 2 is used to shorten the evaluation time.
It is modified such that 0 is cut into short pieces and wound around the transfer roll 32, and the other parts have the same configuration. At this time, as the intermediate transfer belt 20,
The thing which raised the said adhesive force to 0.2 N beforehand was used. This is because the adhesion force of the specific fluororubber constituting the surface layer 22 of the intermediate transfer belt to the toner at the initial stage is as small as about 0.03N, and the release maintaining roll 24
This is to avoid making it difficult to understand the difference in the release agent coating effect when the surface material of e is changed.

The evaluation by the evaluation device 5 was carried out by using various types of release-maintaining rolls 24e as shown in FIG. 12 (aluminum without surface layer only, silicone rubber surface layer-formed, silicone A resin surface layer is formed, a silicone rubber belt is wound as a surface layer, a mold release maintaining roll is not installed, and a fluororesin: PFA surface layer is formed). The reduction amount of the adhesion force of the intermediate transfer belt 20 to the toner when the dimethyl silicone oil is applied from the release agent applying roll 41 to the intermediate transfer belt 20 using the maintenance roll 24e is examined. The dimethyl silicone oil is applied by applying the wound intermediate transfer belt 20 at a peripheral speed of 261 mm / sec.
It was performed by rotating it 0 times. The measurement of the adhesive force is performed by measuring the adhesive force on the intermediate transfer belt 20 which is unused and previously raised,
The adhesive force on the intermediate transfer belt 20 after the oil application was measured. To measure the adhesive force on the intermediate transfer belt 20 after applying the oil, an adhesive force measuring device 2 shown in FIG.
The intermediate transfer belt to be measured was connected to a dummy belt for extension with tape to adjust the length.

The measurement results are shown in FIG. The “adhesive force reduction amount” on the vertical axis in the figure means the difference between the adhesive force before oil application and the adhesive force after oil application, in which the number of prints (here, 125 rotations of the transfer roll 31 is equivalent to 1 kPV. It is divided by the numerical value "5 kPV", which is regarded as the number of sheets and converted.

From the results shown in FIG. 12, it is understood that the amount (effect) of reducing the adhesive force becomes the largest when the oil is applied by using the release maintaining roll 24e made of aluminum alone without forming the surface layer. In particular, this effect is about twice or more as compared with the case where oil is applied without using the release maintaining roll 24e.

Further, the contact angle with respect to dimethyl silicone oil on each surface aspect (shown in FIG. 12) of the release maintaining roll 24e was measured. Contact angle measurement is 5
Wrap the intermediate transfer belt around a 0 mmφ roll, and add dimethyl silicone oil from a syringe with a hole diameter of 0.1 mm.
The contact angle when dropped was measured. FIG. 13 shows the relationship between the measurement result of the contact angle at this time and the above-mentioned adhesive force reduction amount (shown in FIG. 12) of each surface aspect.

From the results shown in FIG. 13, the mold release maintaining roll 2
As a surface material of 4e, when considering from the viewpoint that the effect of reducing the adhesive force is slightly higher than that when the maintenance roll is not used (the amount of adhesive force reduction is about 0.015 N / kPV), it is It can be seen that a material having a contact angle of 20 ° or less is preferable.

Next, the difference in the effect of applying the release agent by changing the temperature condition of the intermediate transfer belt 20 when applying the release agent was examined.

FIG. 14 shows an evaluation device 6 for evaluating the difference in the release agent coating effect depending on this temperature condition.
In this evaluation device 6, the transfer roll 32 and the belt support roll 24 are installed with a space therebetween, and the heating plate 36 and the belt cooling device 3 are arranged between the rolls from the transfer roll 32 side.
7 are installed at intervals, and the intermediate transfer belt 20 is wound around each of the rolls 32 and 24, the heating plate 36, and the cooling device 37, and the intermediate transfer belt 20 between the heating plate 36 and the belt cooling device 37 is Release agent coating roll 41 on the outer peripheral surface
It is a pressure contact. In addition, the release maintaining roll 24e sandwiches the intermediate transfer belt 20 and the transfer roll 32
It is installed in pressure contact with. Reference numeral 38 in the figure is a backup roll of the release agent coating roll 41.

The transfer roll 32 is the same as the transfer roll 32 in the adhesive force measuring device 2 described above, and also serves as a drive roll. The release agent coating roll 41 is the same as that in the release agent coating device 40, and the silicone rubber layer thereof is impregnated with dimethyl silicone oil. Further, the mold release maintaining roll 24e is
It uses metal rolls made of aluminum. The cooling device 37 is configured by combining a heat sink and a blower or intake fan or the like.

The evaluation by the evaluation device 6 is performed by the heating plate 36.
The temperature of the intermediate transfer belt 20 at the pressure contact portion between the transfer roll 32 and the mold release maintenance roll 24e is changed variously as shown in FIG. 15 by interlocking the heating action by the cooling device 37 and the cooling action by the cooling device 37, and the respective temperature conditions are changed. The amount of reduction in the adhesive force of the intermediate transfer belt 20 to the toner when dimethyl silicone oil is applied from the release agent applying roll 41 to the intermediate transfer belt 20 is examined below. The temperature of the intermediate transfer belt 20 at the pressure contact portion is measured by a non-contact type thermometer arranged immediately before the pressure contact portion.
Is measured with respect to the temperature. The application of dimethyl silicone oil was performed under the same application conditions as in the evaluation device 5. In addition, the adhesive force was measured by measuring the adhesive force on the intermediate transfer belt 20 which is unused and increased in advance, and the adhesive force on the intermediate transfer belt 20 after oil application. The measurement of the adhesive force on the intermediate transfer belt 20 after applying the oil was performed using the adhesive force measuring device 2. The measurement result is shown in FIG. "Adhesive force reduction amount" on the vertical axis in the figure is calculated under the same conditions as those in FIG.

From the results shown in FIG. 15, it can be seen that the amount (effect) of reducing the adhesive force increases as the temperature of the intermediate transfer belt 20 when contacting the release maintaining roll 24e increases. Further, the temperature at this time is the same as that of the mold release maintaining roll 24.
Adhesive force reduction amount when e is not used (about 0.015N /
When considered from the perspective of even surpassing kPV),
It can be seen that the temperature is preferably 50 ° C. or higher.

By the way, when the temperature of the intermediate transfer belt 20 at the portion in contact with the release agent coating roll 41 was evaluated in the same manner by the above-mentioned evaluation device 6, the amount of reduction in adhesive force was a little larger when the temperature was higher. However, it is confirmed that it is smaller than the effect of increasing the temperature of the intermediate transfer belt 20 when it comes into contact with the release maintaining roll 24e.

The evaluation by the evaluation device 6 was carried out for the case where the following mold release maintaining roll 24e was used. That is, as the release maintaining roll 24e, one having a surface layer made of silicone rubber having a contact angle of about 20 ° and one having a surface layer made of PFA having a contact angle of about 35 ° were used. . Then, the intermediate transfer belt 20 when coming into contact with each of the release maintaining rolls 24e.
16 is changed variously as shown in FIG. 16, and when the dimethyl silicone oil is applied from the release agent applying roll 41 to the intermediate transfer belt 20 under each temperature condition, the adhesive force of the intermediate transfer belt 20 to the toner is The amount of reduction was investigated. The measurement result is shown in FIG.

From the results shown in FIG. 16, the adhesive force reduction amount (effect) is compared between the case where the surface layer of silicone rubber having a small contact angle is formed and the case where the surface layer of PFA having a large contact angle is formed. As a result, it can be seen that there is a large difference when the temperature of the intermediate transfer belt 20 when it comes into contact with the release maintaining roll 24e is 110 ° C., but the difference is small when the temperature is 160 ° C.

By the way, the evaluation by the evaluation device 6 was also carried out in the same manner as in the case of using the release agent coating roll 41 having another surface layer (the ones listed in FIG. 12). It has been confirmed that when the temperature is increased to about 0 ° C., the difference in the adhesive force reduction amount due to the difference in the material of the surface layer becomes small. This is a mold release maintenance roll 2 having a surface layer with a large contact angle.
Even with 4e, it means that the amount of reduction in the adhesive force can be increased by setting the temperature of the intermediate transfer belt 20 with which the roll contacts to a high temperature of 160 ° C. or higher. In such a case, the selection range of the material forming the surface layer of the release maintaining roll 24e is wide, which is advantageous in the structure of the apparatus.

From the above test results regarding the effect of applying the release agent to the unused intermediate transfer belt, when applying the release agent such as dimethyl silicone oil to the unused intermediate transfer belt 20, the applied surface of the release agent It has been clarified that it is effective to carry out at least the release maintaining roll 24e while contacting it, because the effect of reducing the adhesive force of the intermediate transfer belt to the toner can be obtained.

Next, the unused intermediate transfer belt 20 has a characteristic that the toner adhesion force increases in the belt portion corresponding to the paper passing white background portion of the recording paper P even when the release agent is applied (see FIG. 6). Therefore, before applying the release agent, a blank recording sheet P is brought into contact with the unused intermediate transfer belt 20 to examine the change in the toner adhesion force, and after the release agent is applied, the toner is attached. I examined the change in wearing force.

FIG. 17 shows an adhesion force increasing device 7 for increasing the adhesion force of an unused intermediate transfer belt to toner. This adhesive force raising device 7 excludes the release agent coating roll 41 in the above-mentioned release agent coating dedicated device 4, and installs a pressure contact roll 45 around which the recording paper P is wound in place of the release maintaining roll 24e. Except for the above, it has the same configuration as the dedicated device 4. The pressure roll 45 is a metal roll having an outer diameter of 50 mm, and the recording paper P that can be used for image formation is wound around the roll peripheral surface. The pressure contact roll 45 is in pressure contact with the transfer roll 31 with a pressure load of 600 N, like the release maintaining roll 24e.

The test was conducted in place of the device 7 for exclusive use of the adhesive force,
A process for increasing the toner adhesion force on the unused intermediate transfer belt 20 is performed using the simple adhesion force increase evaluation device 8 shown in FIG. 18, the adhesion force at that time is measured, and then the adhesion force increase process is performed. A release agent (dimethyl silicone oil) was applied to the intermediate transfer belt 20 after the application by the evaluation device 5 for applying the release agent, and the adhesive force at that time was measured. Then, finally, the intermediate transfer belt 20 after applying the release agent is mounted on the adhesive force increase evaluation device 8 again, and a pseudo running test (at this time, the release agent is applied to the intermediate transfer belt 20). (Not applied) was performed and the adhesive force at that time was measured.

The adhesive force increase evaluation device 8 is the same as the above adhesive force exclusive device 7 except that the belt support rolls 24b and 24c are used.
And the two heating plates 36 are omitted, and the unused intermediate transfer belt 20 is cut into a short length in order to shorten the evaluation time.
It has been modified so that it is wound around 1, and has the same structure except the above.

For comparison, the adhesive force is measured by performing only the above-mentioned pseudo running test on the intermediate transfer belt which is not subjected to the above-mentioned adhesive force increasing process and subsequent release agent coating process. Test (condition A in the table)
Then, a test (condition B in the table) was performed in which the pseudo running test described above was performed on the intermediate transfer belt after performing only the release agent coating process to measure the adhesive force. The adhesive force is measured using the above-mentioned adhesive force measuring device 2 and at each processing time indicated by each point shown in FIG.

Table 1 shows each test condition at this time and the breakdown of the adhesive force increasing treatment time and the release agent coating time under each condition. "KPV" shown as a unit of time in the table
Is a unit in which 125 rotations of the transfer roll 31 is converted into 1 kPV for each processing time (almost equivalent to a unit indicating the number of prints).

[0125]

[Table 1]

FIG. 19 shows the result of the test conducted under each of the above conditions A to D. The time “0 kPV” on the horizontal axis in the figure is
The figure shows the end point of the release agent coating process and the start point of the pseudo runnig test. In addition, the numerical value shown as a minus on the horizontal axis is a retrospective representation of the time of the adhesive force increasing process and the release agent coating process performed before that when viewed with "0 kPV" as the reference. is there. In addition, kPV in this figure is also 1 of the transfer roll 31.
It is a unit expressed by converting 25 rotations into 1 kPV.

From the results shown in FIG. 19, when neither the adhesive force raising process nor the release agent coating process is performed on the unused intermediate transfer belt 20 (condition A), the adhesive force of the intermediate transfer belt is running. It is confirmed that the value of the value will decrease sharply as the test progresses.

On the other hand, when at least the release agent is applied (condition B), the amount of increase in the adhesive force after the running test of the intermediate transfer belt is higher than that in the case of condition A. It was confirmed that it could be suppressed (improved). Further, when both the adhesive force increasing step and the release agent coating process are performed (conditions C and D), the intermediate transfer belt of the intermediate transfer belt is more than that when only the release agent coating process is performed (condition B). It was confirmed that the increase in the adhesive force after the running test was further suppressed. Moreover, condition C,
In D, when the adhesion increasing step is executed a lot (condition D), the increase in the adhesion after the running test of the intermediate transfer belt can be suppressed most effectively (for example, about 1 in condition A). It is clear that the rate of increase can be suppressed to about / 20).

From this test result, before applying the release agent to the unused intermediate transfer belt 20, for example, a white background portion of the recording paper P was brought into contact with the toner to increase the adhesive strength to the toner. In that case, the intermediate transfer belt 2
It was found that an increase in toner adhesion force during actual image formation using 0 can be effectively suppressed.

Therefore, the intermediate transfer belt 20 which has been subjected to the releasing pretreatment (adhesive force increasing treatment + releasing agent coating treatment) under the above-mentioned conditions C and D is mounted on the image forming apparatus, and the running test is carried out to carry out the toner. When the degree of change in the adhesive force was examined, the results shown in FIG. 20 were obtained.

As is clear from the results shown in FIG. 20, it is confirmed that the use of the intermediate transfer belt 20 which has been subjected to the pre-mold release treatment significantly suppresses the increase in the toner adhesion force in the initial stage of its use. did it. The effect of suppressing the increase in the adhesive force is excellent even in light of the test results (see FIG. 8) in which the phenomenon of the increase in the adhesive force in the initial stage of use was observed even when the release agent was applied. I know there is.

After the above-mentioned adhesive force increasing process is applied to the unused intermediate transfer belt 20 for some processing time, a releasing agent application process for 12 kPV is performed, and toner after each process is applied. The amount of increase in the adhesive force was examined, and the amount of increase in the adhesive force obtained by dividing each of the increased amounts by the processing time (kPV) was determined, and the relationship between the two was investigated. FIG. 21 shows the relationship between the amount of increase in adhesive force and the rate of increase in adhesive force at this time. On the other hand, a running test was performed using an intermediate transfer belt that had been subjected to the adhesive force increasing treatment of three examples selected arbitrarily from the above-mentioned adhesive force increasing rates, and then subjected to the release agent coating treatment. The release agent was applied by the agent application roll 41), and it was examined to what extent the adhesive force at that time was increased at the maximum. The measurement result is shown in FIG.

From the above-mentioned two test results, as described above, from the viewpoint of setting the whiteout grade to 1 or less, in order to set the maximum value of the adhesive force after the running test to 0.13 N or less, the correlation shown in FIG. The rate of increase in adhesion is about 0.
It can be seen that it is necessary to set it to 025 (N / kPV) or less. In addition, the rate of increase in adhesive force is approximately 0.025 (N / k
It can be seen from the correlation shown in FIG. 21 that the adhesion increasing process of PV) or less may be performed so that the increase of the adhesion is “0.5 N or more”.

Further, a running test was conducted using the intermediate transfer belt 20 in which the release agent application timing was changed for the release pretreatment as described above. It has been confirmed that there is a difference in the degree of increase in the adhesive force of.

Further, the contact angle between the intermediate transfer belt 20 and the dimethyl silicone oil after the release agent coating treatment and the increase rate of the adhesive force by the running test of the intermediate transfer belt 20 were examined. The result shown in FIG. 23 was obtained. From this result, it was confirmed that there is a correlation between the contact angle and the rate of increase in adhesive force. Further, in this case, in order to reduce the maximum value of the adhesive force after the running test to 0.13 N or less, the rate of increase in the adhesive force needs to be about 0.025 (N / kPV) or less. Considering the above, the contact angle must be set to 15 ° or less in order to reduce the adhesive force increase rate to about 0.025 (N / kPV) or less.

Subsequently, the pre-mold release pretreatment as described above (a mold release agent coating process including a step of contacting the mold release maintaining roll, or
(A combination of the release agent application process and the adhesive force increase process)
When an image is formed using the intermediate transfer belt 20 which has been subjected to the test, a test was conducted on the amount of the release agent applied to the intermediate transfer belt 20 by the release agent applying device 40 during the image formation.

In general, when a large amount of dimethyl silicone oil is applied to the surface of the intermediate transfer belt 20 in order to impart releasability to toner, fogging occurs as described above. Here, the fogging is a phenomenon in which a toner image having a very low density is formed in a state of being superposed on the original image. Therefore, as for fogging, the number of fog toners (measured by microscope observation) existing within a certain area of the image when a sample image such as a white paper is formed, and the recording paper P on which the sample image is formed are used. It is possible to make an evaluation using the color difference ΔE of a new recording paper (white paper) in the L * a * b * uniform color space. In fact, the number of fogs and the color difference of the blank sheet have a correlation as shown in FIG.
Here, the number of fogs at which the color difference is 1 or less is an allowable value.

Therefore, the sample image is formed by changing the amount of dimethyl silicone oil applied from the release agent applying device 40 to the intermediate transfer belt 20 (the amount of application per A4 size sheet), and the image is formed. The color difference between the recorded recording paper and a new blank paper was measured. This measurement result is shown in Figure 2.
5 shows. From the results shown in FIG. 25, the coating amount was 0.1
It can be seen that the color difference corresponding to the permissible value of fogging can be set to 1 or less by setting it to 5 μl / A4 or less.

Next, the release agent applying device 40 is applied to the unused intermediate transfer belt 20 which has been subjected to the release pretreatment (condition D) described above.
Dimethyl silicone oil from 0.15 μl /
A running test was conducted while applying the coating amount of A4, and the occurrence of fogging at that time was examined and evaluated as a color difference. In addition, for comparison, the same test was performed using an unused intermediate transfer belt 20 which was not subjected to the pre-release treatment.
Results are shown in FIG. From this result, it can be confirmed that the occurrence of fogging can be suppressed to an allowable level from the initial stage in the case where the release agent pretreatment is applied, as compared with the case where the pretreatment is not applied.

From the above test results and consideration results, in the first embodiment, the intermediate transfer belt 20 is released from the mold by the above-mentioned device 3 for applying the mold release agent in the unused stage before being mounted on the image forming apparatus. A release agent coating process as a pretreatment is performed, or the adhesion force increasing process is performed as a partial treatment step of the mold release pretreatment by the above-described device 6 for increasing the adhesion force before performing the release agent applying process. I tried to use the one I did.

As a result, according to the image forming apparatus 1A according to the first embodiment, since a new intermediate transfer belt 20 which has been subjected to the pre-mold release treatment is mounted and used, the initial stage of use (maximum) It is possible to suppress the phenomenon that the adhesive force to the toner increases when the release agent is applied to the intermediate transfer belt before the number of prints reaches about 5 kPV (as a result). In addition, it is possible to prevent the occurrence of image defects such as image offset and white spots due to the residual adhesion of toner on the intermediate transfer belt. Further, since it becomes possible to suppress the increase of the toner adhesion force of the intermediate transfer belt in the initial stage of use as described above, it is not necessary to apply a large amount of the release agent to prevent the increase of the adhesion force.
As a result, it is possible to prevent fogging and the occurrence of oil streaks on the photosensitive drum 11 due to excessive application of the release agent.

[Modification of First Embodiment] The mode in which the release pretreatment is performed before the intermediate transfer belt 20 is mounted in the image forming apparatus has been described above. After mounting it on the image forming device as it is,
The release pretreatment may be performed in the image forming apparatus.

Specifically, in a state in which the toner image is not formed by the image forming unit 10, a blank recording sheet P is supplied to the unused intermediate transfer belt 20 in the same manner as at the time of transfer fixing, and is passed therethrough. Then, the adhesive force increasing process is performed as a release pretreatment, and thereafter, with the supply of the recording paper P stopped,
A release agent is applied from the release agent application roll 41 of the release agent supply device 40 to the intermediate transfer belt 20 after the adhesion increasing process, and the release maintaining roll 24e is brought into contact with the application surface to release the release agent. A release agent coating process is performed as a pretreatment. If necessary, the adhesive force increasing process by passing the recording sheet and the release agent applying process by the release agent applying device 40 may be set to be executed at the same time. On this occasion,
The release agent coating device 40 also serves as a release processing device. In the case where the mold release pretreatment is performed in the image forming apparatus as described above, the processing operation is incorporated as an instruction operation from the operation panel or one operation of the initialization mode, for example, when the assembly of the image forming apparatus is completed. It may be configured to be performed in the factory or at the user's installation site.

Further, in the case of such an embodiment, instead of or in addition to the release maintaining roll 24e used in the release agent coating process, the intermediate transfer belt 20 facing the heating plate 36.
The mold release maintaining roll 24g may be arranged so as to contact the outer peripheral surface of the (see FIG. 2). In this case, the portion of the intermediate transfer belt 20 with which the release maintaining roll 24g abuts is heated by the heating plate 36 to a predetermined temperature (for example, 50 ° C. or higher, or 16
(0 ° C. or higher) can be efficiently and quickly heated, and the coating efficiency of the release agent can be improved. However,
The release maintaining roll 24g, which comes into contact with the position of the intermediate transfer belt 20 that conveys the toner image before transfer and fixing, is installed so that it can be brought into contact with and separated from the belt 20 by a retract mechanism. It must be configured to abut only at run time.

Further, in the case of such a mode, it becomes possible to appropriately perform the pre-release processing on the used intermediate transfer belt 20.

In the case of the mode in which the release pretreatment is performed on the intermediate transfer belt 20 before being mounted on the image forming apparatus 1A, the adhesion increasing device 6 is provided at a predetermined position of the release agent applying device 3. Pressure roll 4 wrapped around recording paper in
5 may be installed, and the adhesion force increasing process by the pressure contact roll 45 may be performed almost simultaneously with the release agent applying process.

[Second Embodiment] FIG. 27 shows a second embodiment.
2 shows an essential part of a color image forming apparatus 1B according to the present invention. The color image forming apparatus 1B has the same configuration as the image forming apparatus 1A according to the first embodiment except that a fixing auxiliary belt 50 is added to the transfer fixing unit. In the figure, the fixing auxiliary belt 50 is shown by a dotted line for convenience.

The fixing auxiliary belt 50 is, as described above,
It is mainly installed in order to suppress the occurrence of blisters, and therefore, is installed in a state where it contacts the outer peripheral surface of the intermediate transfer belt 20 at least between the transfer roll 32 and the supporting roll 24c for peeling. Has been done. In the second embodiment, the fixing auxiliary belt 50 is connected to the transfer roll 3
1 and the pressure contact roll 51 installed in front of the peeling support roll 24c, and between the transfer roll 31 and the pressure contact rolls 51 and 52, the intermediate transfer belt 20.
It is installed so that it can rotate in contact with. Reference numeral 56 in the drawing is a cleaning roll for cleaning the surface of the fixing auxiliary belt 50. As the fixing assist belt 50, a double structure having a surface layer formed on a predetermined belt base material is used. As the surface layer, the intermediate transfer belt 2
It is possible to apply a material formed of the same material as the surface layer 22 of No. 0 (particularly, a specific fluororubber).

Thus, the transfer fixing position (transfer roll 3
1, the recording paper P is conveyed while being pressed against the intermediate transfer belt 20 from the pressure contact portion between 1 and the intermediate transfer belt 20) to the paper peeling portion (installation position of the support roll 24c), and adheres to the intermediate transfer belt 20. The sex will be maintained. As a result, it is possible to prevent vapor from entering and remaining between the recording sheet and the toner image, and thus it is possible to suppress blister.

However, such a fixing auxiliary belt 50 is
When using, for example, double-sided image formation (double-sided printing)
Then, the fixing toner image formed on the first surface of the recording paper P is brought into contact with the fixing auxiliary belt 50 during transfer and fixing onto the second surface of the recording paper P. When the adhesion is high, the toner image on the first surface may be offset and adhered to the fixing auxiliary belt 50. When the toner adheres to the fixing assist belt 50, the image defects such as the image offset and the white spot as described above are caused. Moreover, in this case, even if the surface of the fixing auxiliary belt 50 is simply coated with the release agent coating device (release agent coating roll) 55, a problem due to excessive coating of the release agent is induced.

Therefore, similarly to the case of the intermediate transfer belt 20 in the first embodiment, the fixing auxiliary belt 50 is not released from the fixing auxiliary belt 50 in the unused stage before being mounted on the image forming apparatus 1B. The image forming apparatus 1B is provided with a mold release processing device as a mold release pretreatment, and the unused fixing auxiliary belt 50 is subjected to the mold release pretreatment by the mold release processing device. There is.

When pre-release processing is performed on the fixing auxiliary belt 50 before mounting, the release agent application processing is performed by using the release agent application apparatus 4 (FIG. 10) as exemplified in the first embodiment. In addition, the adhesion force increasing device 7 (FIG. 17) is used to perform the adhesion force increasing process. At this time, the processing conditions and the like in the release agent coating process and the adhesive force increasing process can be the same as those in the first embodiment.

On the other hand, when pre-release processing is performed in the image forming apparatus 1B, the release agent coating device 55 is also used as a release processing device, and the release maintaining roll 53 is provided on the downstream side in the belt rotating direction. Install. As a result, the release agent is applied to the unused fixing auxiliary belt 50 and the release maintaining roll 53 is brought into contact with the application surface thereof, and thus the release agent application process as the release pretreatment is performed. It When the adhesive force increasing process is performed in addition to the release agent applying process, a blank recording sheet P is supplied and the intermediate transfer belt 20 and the fixing assist belt 50 are fed, as in the case of the first embodiment. Pass in between.

Even in the image forming apparatus 1B,
Embodiment 1 for the unused intermediate transfer belt 20
It goes without saying that the same pre-molding treatment as in the above case is performed.

[Third Embodiment] FIG. 28 shows a third embodiment.
2 shows an essential part of a color image forming apparatus 1C according to the above. This color image forming apparatus 1C employs a method in which a transfer section (secondary transfer section) and a fixing section are independent of each other, instead of the transfer fixing method in the image forming apparatus 1A according to the first embodiment, and the transfer section has the independent structure. An image forming apparatus except that a part of an intermediate transfer unit including the intermediate transfer belt 20 is changed for matching and a belt fixing device 60 using a fixing belt is newly used for matching with the fixing part. It has almost the same configuration as 1A.

In addition to the drive roll 23 and the belt support rolls 24a and 24b, the intermediate transfer belt 20 includes a secondary transfer backup roll 34 and a secondary transfer roll 35 which are installed at positions downstream of the belt support roll 24b in the belt rotation direction.
Partly changed so as to rotate in the direction of arrow B by being wrapped around the two rolls 34, 35 and the two belt support rolls 24h, 24i installed between the drive rolls 23.

Particularly, the secondary transfer portion of the intermediate transfer belt 20 (the portion where the rolls 34 and 35 related to the secondary transfer are arranged)
The belt support roll 24h is brought closer to the image forming unit side so as to secure a space space S recessed inward for accommodating and installing the belt fixing device 60 in a section after passing through the drive roll 23. A belt support roll 24i, which is arranged at a position and which stretches the intermediate transfer belt 20 after passing through the belt support roll 24h to the drive roll 23, is arranged immediately before the drive roll 23. In the image forming apparatus 1C, the toner image transferred onto the intermediate transfer belt 20 does not need to be heated before the secondary transfer. Therefore, the heating plate 36 used in the first embodiment adopting the intermediate transfer system is used. Is not installed.

The belt fixing device 60 includes a fixing belt 61.
Is wound around a roll 62 of the pair of fixing rolls 62 and 63 and a plurality of belt supporting rolls 64a to 64d, and is rotated in the direction of arrow C by the driving force of the fixing roll 63 which also serves as a driving roll. There is. The fixing device 60 is heated by a belt heating plate 65 installed between the belt supporting rolls 64c and 64d. The fixing rolls 62 and 63 are provided with an electric heater inside the rolls so that the surface of the rolls is heated to a temperature higher than the melting temperature (softening point) of the toner. In the figure, reference numeral 66 is a cleaning roll for cleaning the surface of the fixing roll 63, and 67 is the fixing belt 6.
1 is a cleaning roll for cleaning the surface of the sheet 1, 68 is a backup roll of the cleaning roll 67, and 69 is a sheet conveying device installed between the secondary transfer portion and the fixing device 60.

Image formation by the color image forming apparatus 1C is generally performed as follows. First, as in the case of the image forming apparatus 1A according to the first embodiment, after the toner images of the respective colors are formed on the photosensitive drum 11 by the image forming unit 10, the respective toner images are primarily transferred onto the intermediate transfer belt 20. It The toner image transferred to the intermediate transfer belt 20 is
It is electrostatically secondarily transferred to the recording paper P which is supplied and fed between the intermediate transfer belt 20 and the secondary transfer roll 35.

Then, the recording paper P on which the toner image is transferred
Is fed to the belt fixing device 60 by the sheet conveying device 69. In the belt fixing device 60, the belt heating plate 65
The fixing belt 61 is heated by the fixing rolls 62 and 63. As a result, the toner image on the recording paper P is heated and pressed between the fixing belt and the fixing roll 63 (pressure contact portion) and fixed on the paper. Then, the recording paper P that has passed through the pressure contact portion is conveyed to a peeling position where the supporting roll 64a functioning as a peeling roll is present while being in close contact with the outer peripheral surface of the fixing belt 61, and is cooled in the process. . By this cooling, the heat-melted toner is sufficiently aggregated and solidified and strongly fixed on the paper side. The recording paper P thus cooled is peeled off from the fixing belt 61 by itself at the peeling position.

As a result, a color image or the like is formed on one side of the recording paper P. At this time, the image formed of the toner formed on the recording paper P has a rich glossiness because the surface smoothness of the fixing belt 61 is directly transferred to the image surface.

However, such a belt fixing device 60
Also in the above, if the adhesion force of the fixing belt 61 to the toner is high, the toner image on the recording paper P may be offset and adhere to the fixing belt 61. When the toner adheres to the fixing belt 61 as described above, the image defects such as the image offset and the white spot as described above are caused. Moreover, in this case, even if the surface of the fixing belt 61 is simply coated with the release agent coating device (release agent coating roll) 70, a problem due to excessive coating of the release agent is induced.

Therefore, also for the fixing belt 61,
Similar to the case of the intermediate transfer belt 20 in the first embodiment, the fixing belt 61 in the unused stage before being mounted on the image forming apparatus 1C and then the fixing device 60 is subjected to pre-release processing or its fixing. The apparatus 60 is provided with a mold release processing apparatus as a mold release pretreatment, and the unused fixing belt 61 is subjected to the mold release pretreatment by the mold release processing apparatus.

When the release belt pretreatment is performed on the fixing belt 61 before mounting, the release agent application treatment is performed by using the release agent application apparatus 4 (FIG. 10) as exemplified in the first embodiment. ,
Further, the adhesion increasing process is performed by using the adhesion increasing device 7 (FIG. 17). At this time, the processing conditions and the like in the release agent coating process and the adhesive force increasing process can be the same as those in the first embodiment.

On the other hand, when the mold release pretreatment is performed in the image forming apparatus 1C and then in the fixing device 60, the mold release agent applying device 7 is used.
0 is also used as a mold release processing device, and a mold release maintaining roll 71 is installed on the downstream side in the belt rotation direction. As a result, the release agent is applied to the unused fixing belt 61 and the release maintaining roll 71 is brought into contact with the application surface,
Accordingly, a mold release agent coating process is performed as a mold release pretreatment.
When the adhesive force increasing process is performed in addition to the release agent applying process, the blank recording paper P is supplied to the intermediate transfer belt 20 and the fixing belt 61 as in the case of the first embodiment.
Pass between.

[Fourth Embodiment] FIG. 29 shows a fourth embodiment.
2 shows a main part of the color image forming apparatus 1D according to the present invention. The color image forming apparatus 1D basically has the same configuration as the image forming apparatus 1C according to the third embodiment except that a fixing auxiliary belt 80 is added to the fixing device 60. The fixing auxiliary belt 80 is shown by a dotted line for convenience.

The fixing auxiliary belt 80 is, as described above,
It is installed mainly for suppressing the occurrence of blister, and therefore, it is installed in a state of being in contact with the outer peripheral surface of the fixing belt 61 at least between the fixing roll 63 and the peeling support roll 64a. There is. In the fourth embodiment, the fixing auxiliary belt 80 includes the fixing roll 63,
It can be wound around one of a pair of pressure contact rolls 82, 83 installed at the front position of the support roll 64a for peeling the paper, and can rotate while being in contact with the fixing belt 61 between the fixing roll 63 and the pressure contact roll 83. Is installed as. Reference numeral 84 in the drawing is a cleaning roll for cleaning the surface of the fixing auxiliary belt 80. Fixing auxiliary belt 8
As 0, a double structure having a surface layer formed on a predetermined belt base material is used. As the surface layer, one formed of the same material as the surface layer 22 of the intermediate transfer belt 20 (particularly, a specific fluororubber) can be applied.

As a result, the recording paper P is conveyed while being pressed against the fixing belt 61 from the fixing position (the pressure contact portion between the fixing roll 63 and the fixing belt 61) to the paper peeling portion (the installation position of the support roll 64a). As a result, the adhesion with the belt 61 is maintained. As a result, it is possible to prevent vapor from entering and remaining between the recording sheet and the toner image, and thus the occurrence of blisters is suppressed.

However, such a fixing auxiliary belt 80
In the same manner as the case of the fixing auxiliary belt 50 in the second exemplary embodiment, when the double sided image formation (double sided printing) is performed, the toner image on the first surface is offset to the fixing auxiliary belt 80. The particles adhere to each other and cause the image defects such as the image offset and the white spot as described above. Moreover, in this case, the release agent applying device (release agent applying roll) 90 is simply applied to the surface of the fixing assist belt 80.
Even if it is applied by the above method, a problem due to excessive application of the release agent is induced.

Therefore, similarly to the case of the fixing auxiliary belt 50 in the second embodiment, the fixing auxiliary belt 80 is in the unused stage before being attached to the image forming apparatus 1D and then the fixing apparatus 60. To the fixing device 60, or a releasing treatment device as a releasing pretreatment is installed in the fixing device 60, and the unused fixing auxiliary belt 80 is subjected to the releasing pretreatment by the releasing treatment device. I am trying.

In the case where pre-release processing is performed on the fixing auxiliary belt 80 before mounting, the same structure as described in the second embodiment can be adopted. On the other hand, when the pre-release processing is performed in the fixing device 60, the release agent coating device 90 also serves as the release processing device, and the release maintaining roll 91 is installed on the downstream side in the belt rotation direction. As a result, the release agent is applied to the unused fixing auxiliary belt 80 and the release maintaining roll 91 is brought into contact with the application surface thereof, and thus the release agent application process as the release pretreatment is performed. It When the adhesive force increasing process is performed in addition to the release agent applying process, the blank recording paper P is supplied between the fixing belt 61 and the fixing auxiliary belt 80 as in the case of the third embodiment. To pass.

Even in this image forming apparatus 1D,
It goes without saying that the unused pre-fixing belt 61 in the fixing device 60 is subjected to the same pre-release processing as in the case of the third embodiment.

[0173]

As described above, according to the present invention,
It has an image bearing member that carries a toner image and a fixing belt that fixes the toner image on the recording paper. At the stage of use, a release agent is applied to the surface of the image bearing member, the fixing belt, etc. to release the toner. Even in an image forming apparatus that secures the property, it is possible to suppress the adhesion of the surface of the image carrier, the fixing belt, or the like to the toner at the initial stage of use, without causing contamination due to the application of the release agent. . As a result, it is possible to reduce the occurrence of image defects such as image offset and white spots in the initial stage of use due to the increase in the toner adhesion force of the image carrier and the fixing belt. In addition, since it is not necessary to increase the coating amount of the first release agent in order to suppress the increase in the adhesive force in the initial stage of use, the problem of contamination due to the excessive coating of the release agent can be avoided.

[Brief description of drawings]

FIG. 1 is an explanatory view schematically showing a state of toner adhesion force on an intermediate transfer belt or the like when a release agent treatment is performed in the present invention and a state of the adhesion force at an initial stage of use after the treatment. .

FIG. 2 is a schematic diagram showing a main part of the image forming apparatus according to the first embodiment.

FIG. 3 is a schematic diagram showing a main part of an image forming unit.

FIG. 4 is a sectional view showing an intermediate transfer belt.

FIG. 5 is a conceptual diagram schematically showing a force relationship between an intermediate transfer belt and a recording sheet when molten toner is present.

FIG. 6A is a plan view illustrating an adhesive force measuring device for measuring an adhesive force with respect to toner, and FIG. 6B is a plan view showing a recording sheet used in the measurement and a toner image formation state.

FIG. 7 is a graph showing the measurement results of the adhesive force with respect to a paper passing white background portion and a paper passing patch portion.

FIG. 8 is a graph showing the measurement results of the adhesive force when the release agent is applied and when the release agent is not applied.

FIG. 9 is a correlation diagram showing the relationship between the adhesive force and the white spot grade.

FIG. 10 is a schematic view showing a main part of a device for exclusive use in release agent coating processing.

FIG. 11 is a schematic view showing a main part of a release agent application evaluation apparatus.

FIG. 12 is a graph showing the measurement results of the amount of reduction in the adhesive force of the release maintaining roll to the surface material and the like.

FIG. 13 is a graph showing the measurement results of the contact angle and the adhesive force reduction amount.

FIG. 14 is a schematic diagram showing a main part of an apparatus for evaluating release agent application conditions.

FIG. 15 is a graph showing the measurement results of the adhesive force reduction amount with respect to the temperature condition of the intermediate transfer belt portion.

FIG. 16 is a graph showing the measurement results of the temperature condition and the adhesive force reduction amount at the contact portion of the intermediate transfer belt having different surface layers with the release maintaining roll.

FIG. 17 is a schematic view showing a main part of an apparatus for exclusive use in an adhesion amount increasing process.

FIG. 18 is a schematic diagram showing a main part of an evaluation device for an adhesion amount increase test.

FIG. 19 is a graph showing the measurement results of each adhesive force at the time of pretreatment for mold release and after the treatment.

FIG. 20 is a graph showing the measurement results of the adhesive force of the intermediate transfer belt after the pre-release processing is performed.

FIG. 21 is a correlation diagram showing the relationship between the amount of increase in adhesion and the rate of increase in adhesion.

FIG. 22 is a correlation diagram showing the relationship between the adhesive force increase rate and the adhesive force.

FIG. 23 is a graph showing the measurement result of the contact angle of the intermediate transfer belt after the release pretreatment.

FIG. 24 is a graph showing the measurement results of the number of fogs and the color difference.

FIG. 25 is a graph showing the measurement results of oil application amount and color difference.

FIG. 26 is a graph showing the measurement results of the presence / absence of release pretreatment and the color difference.

FIG. 27 is a schematic diagram showing a main part of the image forming apparatus according to the second embodiment.

FIG. 28 is a schematic diagram showing a main part of the image forming apparatus according to the third embodiment.

FIG. 29 is a schematic diagram showing a main part of an image forming apparatus according to a fourth embodiment.

FIG. 30 is a graph showing the measurement results of adhesive force during a running test.

FIG. 31 is a schematic diagram showing a main part of an image forming apparatus adopting a conventional intermediate transfer system.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 20 ... Intermediate transfer belt (image carrier), 24e, 56, 7191 ... Release maintaining roll (contact member), 30 ... Transfer fixing device (transfer fixing unit), 40,
55, 70, 90 ... Release agent applying device (release agent applying means or release processing means), 61 ... Fixing belt, 50, 80 ... Fixing auxiliary belt, 60 ... Fixing device, P ... Recording paper.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazuhiko Arai             430 Sakai, Nakai-cho, Ashigarakami-gun, Kanagawa Prefecture             Inside, Fuji Xerox Co., Ltd. (72) Inventor Yuka Nakayama             430 Sakai, Nakai-cho, Ashigarakami-gun, Kanagawa Prefecture             Inside, Fuji Xerox Co., Ltd. (72) Inventor Hiroyuki Suzuki             430 Sakai, Nakai-cho, Ashigarakami-gun, Kanagawa Prefecture             Inside, Fuji Xerox Co., Ltd. F term (reference) 2H033 AA02 AA09 BA42 BA43 BA46                       BB01 BB28 BE09                 2H078 AA08 AA10 AA13 BB01 BB12                       CC06 DD03 DD51 DD53 DD57                 2H200 FA07 FA08 FA17 GA12 GA23                       GA33 GA34 GA44 GA47 GB12                       GB22 GB23 GB25 GB27 HA03                       HA12 HB03 HB12 HB22 JA02                       JA07 JA08 JA21 JA25 JA27                       JC03 JC09 JC12 JC13 JC15                       JC17 LC10 MA01 MA03 MA04                       MA08 MA14 MA20 MB04 MC01                 4F040 AA20 AB08 AC01 BA07 CB02                       CB28

Claims (12)

[Claims] 1. An image carrier that carries a toner image on its surface and rotates, and a toner image on the image carrier is heated and heated at least on a recording sheet supplied so as to contact the surface of the image carrier. An image forming apparatus comprising: a transfer fixing unit that applies pressure to transfer and fixes the image; and a release agent applying unit that applies a first release agent to the surface of the image carrier, wherein the image carrier is at least in an unused stage. The image forming apparatus is characterized in that the second release agent is applied to the surface thereof and a release pretreatment is performed to bring the contact member into contact with the application surface. 2. A mold release processing means provided with a coating means for coating a second release agent on at least an unused surface of the image carrier and a contact member for contacting the coating surface. The image forming apparatus according to claim 1, wherein at least the release pretreatment is performed by the release processing means. 3. The release pretreatment is a treatment for increasing the adhesive force for increasing the adhesive force of the surface of the image carrier to the toner image before or at the same time as applying the second release agent. Or the image forming apparatus according to 2. 4. A fixing means for supplying a recording paper carrying a toner image to be fixed so as to contact the surface of a rotating fixing belt, and fixing and fixing the toner image on the recording paper by at least heating and pressurizing the fixing paper. An image forming apparatus having a releasing agent applying unit for applying a first releasing agent to a surface of a fixing belt of a fixing unit, wherein the fixing belt applies a second releasing agent to the surface of the fixing belt at least in an unused stage. In addition, the image forming apparatus is characterized by being subjected to a pre-release treatment for bringing the abutting member into contact with the coating surface. 5. A mold release processing means comprising: a coating means for coating a second release agent on at least an unused surface of the fixing belt; and a contact member for contacting the coating surface, The image forming apparatus according to claim 4, wherein at least the release pretreatment is performed by the release processing means. 6. The release pretreatment is a treatment which is also performed before or at the same time as applying the second release agent, together with an adhesive force increasing process for increasing the adhesive force to the toner image on the surface of the fixing belt. The image forming apparatus according to 4 or 5. 7. An image carrier that carries a toner image on its surface and rotates, and at least heat and apply the toner image on the image carrier to the recording paper supplied so as to contact the surface of the image carrier. Transfer fixing means for pressing and transferring and fixing, a fixing assisting belt rotating in contact with a surface portion between the transfer fixing position of the image carrier and the recording paper separating position, the image carrier and fixing assist An image forming apparatus having a release agent applying unit for applying a first release agent to each surface of the belt, wherein the image carrier and the fixing auxiliary belt have a second release agent on each surface in at least an unused stage. An image forming apparatus, characterized in that a release pretreatment for applying an agent and bringing an abutting member into contact with each application surface is performed. 8. An application means for applying a second release agent to at least unused surfaces of the image bearing member and the fixing auxiliary belt, and an abutting member for abutting each application surface. The image forming apparatus according to claim 7, further comprising: a mold release processing unit, wherein at least the mold release pretreatment is performed by the mold release processing unit. 9. The pre-release treatment is also performed before or at the same time as applying the second release agent, together with an adhesive force increasing process for increasing the adhesive force of each surface of the image carrier and the fixing auxiliary belt to the toner image. The image forming apparatus according to claim 7, which is processing to be performed. 10. Fixing means for supplying a recording paper carrying a toner image to be fixed so as to contact the surface of a rotating fixing belt, and fixing and fixing the toner image on the recording paper by at least heating and pressurizing the recording paper. A fixing auxiliary belt that rotates in contact with a surface portion between a fixing position and a recording paper peeling position of the fixing belt of the fixing unit, and a first release agent is applied to each surface of the image carrier and the fixing auxiliary belt. In the image forming apparatus having the releasing agent applying unit, the fixing belt and the fixing auxiliary belt apply the second releasing agent to each surface of the fixing belt and the fixing auxiliary belt at least in an unused stage, and contact the respective application surfaces with the second releasing agent. An image forming apparatus, characterized in that a pre-release process for bringing the sheet into contact is performed. 11. A mold release comprising coating means for applying a second release agent to at least unused surfaces of the fixing belt and the auxiliary fixing belt, and an abutting member for abutting the application surface. The image forming apparatus according to claim 10, further comprising a processing unit, wherein at least the release pretreatment is performed by the release processing unit. 12. The pre-release treatment is also performed before or at the same time as applying the second release agent, together with an adhesive force increasing process for increasing the adhesive force of the respective surfaces of the fixing belt and the fixing auxiliary belt to the toner image. The image forming apparatus according to claim 10, which is processing.